Colon Ecology, Probiotics, and Prebiotics

The colon is a dynamic ecologic system in which human colon cells and immune cells, microbes and ingested foods interact in the near-absence of oxygen. The human gastrointestinal tract normally contains trillions14 of living bacteria, representing over 400 individual species. Most live in the colon. The goal of dietary maintenance of colon health is to foster a symbiotic relationship, with the human host and its microbial guests living in harmony and balance.

The colon harbors a large variety of microorganisms. The most common bacterial species in the healthy human colon are the Bifidobacteria and Lactobacilli. In addition, even the healthy colon normally contains pockets of Clostridia, yeasts and protozoa. The species of bacteria that most quickly and efficiently produce butyrate in the human colon, and which therefore are the most beneficial and the most desirable, are the Bifidobacteria and Lactobacilli.

Beneficial Probiotic Organisms

The Bifidobacteria are the most common microorganisms in the healthy human digestive tract and are the predominant microbes in human breast milk. Bifidobacteria comprise about 50% of all intestinal microflora in the healthy colon and ferment dietary fiber to short chain fatty acids, especially butyrate. By producing large amounts of butyrate, the Bifidobacteria support the health and function of human colon cells. In addition, the Bifidobacteria suppress the growth of harmful bacteria by keeping the acidity of the colon interior just high enough to inhibit bacterial growth but not too high to affect the colon cells. Bifidobacteria also compete with unhealthy bacteria for space within the colon.

Lactobacilli (the “lactic acid bacteria”) comprise about 25% of all intestinal microflora. The Lactobacilli perform many of the same colon-friendly functions as the Bifidobacteria but produce a little more lactic acid, helping the Bifidobacteria keep the colon slightly acidic. The Lactobacilli also secrete an enzyme that breaks down lactose from milk.13

Species of Saccharomyces, a yeast commonly living in both the small and large intestines, help stimulate intestinal digestive activities. In addition, they are antagonistic to Candida albicans and keep them at bay. These yeasts also enhance immunity in the gut and dietary supplementation with Saccharomycesboulardii has been found to support the consistency of healthy bowel movements.14

The most common and beneficial bacteria and yeasts share an important fundamental characteristic. They all prefer to feast on soluble dietary fiber. Feed them and they will produce all the butyrate your colon can eat. Starve them and risk the health of your colon.

Disturbances of Colon Ecology

The colon is a dynamic system. Its health is directly influenced by our dietary choices. These choices impact the supply of nutrition to the gut bacteria and our intestinal cells. A number of common dietary and medical practices can disturb the symbiotic relationship between microorganisms and human cells that is absolutely vital to the health of the colon. Among these are infant formula feeding, low fiber diets, and oral antibiotic therapy.

Infant Formula Feeding — The human gastrointestinal tract is sterile at birth. During birth, the tract is seeded initially by organisms living in the maternal vagina. During breastfeeding, mammary gland microflora contribute the early populations of Bifidobacteria that begin to populate the infant’s colon. Food borne microflora and self-inoculation also contribute to early intestinal ecology. Species distribution in the newborn digestive tract is modulated for the first few days of life by maternal antibodies transferred in colostrum. In breastfed infants, over 90% of intestinal bacteria consist of Bifidobacterium infantis. In contrast, the intestinal tracts of infants who are not breastfed are characterized by low numbers of Bifidobacteria and Lactobacilli and high numbers of less healthy Enterococci, Coliforms and Clostridia. The lack of proper healthy gut bacterial species in childhood has been associated with a number of digestive health issues.14

Low Fiber Diets — Lack of dietary fiber for fermentation reduces the supply of butyrate available to colon cells and interferes with their ability to seal the colon off from the bloodstream, increasing the likelihood of toxins and bacteria from the guts entering circulation. As discussed above, butyrate starvation also slows the renewal of colon cells. Insufficient amounts of nonfermentable fiber slows the rate of passage of the digesta, increasing the time available for water absorption by colon cells and providing increased exposure of the longer-lived colon cells to free radicals.15 Increased water absorption results in stool hardness and affects the consistency of bowel movements.16 Fiber provides the food for intestinal bacteria and the bulk for optimal bowel function.

Oral Antibiotic Therapy — Antibiotics can also kill beneficial Lactobacilli and Bifidobacteria. As the numbers of these beneficial bacteria decrease, there is a compensatory increase in the unhealthy species that have been kept under control by the beneficial bacteria, resulting in disturbances in gut ecology. This shift in microbial populations can have a severe impact on colon health. Most importantly, this disturbance of gut ecology may lead to decreased levels of butyrate as most of the overgrown microbial species are inefficient fermenters of dietary fiber. The combination of reduced ability to seal off the colon and increased populations of unhealthy organisms can compromise the colon lining and affect immune function.

Supplemental Prebiotics and Probiotics

The colon is dependent on its microbial residents for nourishment and defense. In turn, our microbes need to eat foods that are healthy for them. Ideally, good food sources of fiber would have been a major part of our diet all of our life, and our colon and its residents would require very little attention from us. Realistically, the average American is fiber deficient and has a colon to reflect it. Restoring the healthy ecological balance in the colon is absolutely mandatory if health and healthy aging are your objectives.

Prebiotics — Starter Foods for Your Microbes

Prebiotics are dietary ingredients often consumed in the form of foods and dietary supplements that stimulate the growth of Bifidobacteria and Lactobacilli species and foster the production of butyrate within the colon. The most widely available prebiotics are fructans (fructooligosaccharides; FOS), inulin and the oligofructoses, galactooligosaccharide and the levans (occurring in tubers and grasses). Foods that contain large amounts of these prebiotics include wheat, onions, asparagus, chicory, banana and artichokes.

These compounds all are indigestible by humans within the small intestine, are converted to short chain fatty acids in the colon and are essentially calorie-free. Fructooligosaccharides (FOS) – These long-chain indigestible sugars are specifically fermented to short-chain fatty acids (especially butyrate) by Bifidobacteria. The results of a study published recently in the Nutrition Journal confirm that the daily consumption of as little as 2.5 g of FOS increases the proportion of Bifidobacteria in the colon.17 The consumption of FOS by infants has been documented to be safe and to decrease the incidence of infant emesis and regurgitation. In addition to fostering colon health, the products of FOS fermentation may promote cardiovascular health.

Probiotics — Dietary Supplements to Repopulate Your Colon

Probiotics have been defined as oral dietary supplements containing live microbes that enhance colon health. When effective, such supplements increase the numbers of intestinal Bifidobacteria and Lactobacilli and decrease the numbers of those microbial species that do not produce butyrate. An ideal probiotic supplement will have the following characteristics:

1) The bacteria must survive passage through the stomach and small intestine so that they reach the colon while still alive,

2) They must produce short-chain fatty acids from dietary fiber while in the colon

3) They must maintain a slightly acidic colonic pH, and 4) They must be capable of eventually permanently repopulating the colon themselves or stimulate other healthy bacterial species to do so.

As suggested by the results of a recently published study, successful reseeding of the colon’s microbial populations can support increased immune defenses.18 According to articles published recently in Gut and the American Journal of Physiology, this benefit may result from an effect of the probiotic organisms leading to an increase in the stimulation and vigilance of the immune cells that are interspersed within the lining of the colon.19,20

Successful reseeding with probiotic species requires at least 6 months of daily ingestion of at least 10 billion “colony forming units” (1010 CFU) per species. Successful reseeding may not be possible in some individuals with chronically compromised colon health; they may well require life-long daily supplementation in order to maintain appropriate microbial populations in their colon.

Bacillus coagulans: A Novel, Unique Probiotic Organism

Bacillus coagulans is a bacterial species that may offer unique benefits to digestive health. This bacterium is a spore former and is especially hardy with respect to different intestinal environments. A specific strain of Bacillus coagulans known as BC30™ is available as a dietary supplement for digestive health. Research indicates that this particular strain has beneficial immune effects while it also enhances the repopulation of the digestive tract with other friendly bacterial strains. While BC30™ is a transient organism in that it does not colonize the digestive tract itself, it promotes optimal gut ecology and aids in crowding out other non-beneficial organisms.

BC30™ can be an effective nutritional tool on its own or in combination with other multi-strain probiotic dietary supplements to support digestive tract wellness. Since BC30™ is a spore former and is a hardy strain of bacteria; it does not need to be refrigerated.

Combinations of Prebiotics and Probiotics

Because probiotics are the bacteria you want to live in your colon and prebiotics are the food they love best, it would make sense to combine the two, so that you can be sure that the newly-arriving residents have plenty to eat after their trip through your digestive tract. The benefits of “combination supplementation” are well-documented.

The published human clinical trials have been summarized recently in the Journal of Bioscience and Bioengineering and the World Journal of Gastroenterology.14,21 This large body of scientific evidence demonstrates conclusively that dietary supplementation with prebiotic/probiotic combinations consistently yields health benefits that extend beyond digestive wellness on several fronts. A review article published recently in the World Journal of Gastroenterology recommended Lactobacillus-containing “combination supplements” for enhancing digestion of lactose.22 Conversely, because it encourages normal water management by colon cells and healthy contractions by colonic smooth muscles, “combination supplementation” also promotes the consistency of healthy bowel movements.21,23

The Bottom Line

Maintaining healthy digestive function consists of supporting multiple aspects of the complicated physiological function of the gastrointestinal system. While the process of digestion itself is complex, supporting several fundamental aspects of the process can lead to tangible benefits for overall health. Dietary factors are critical as the foundation for digestive health. This entails consuming foods that are healthy and eating an adequate amount of dietary fiber. Nutritional interventions are also a key element. These include supplemental enzymes, fiber supplements, prebiotics and probiotics. An optimally functioning digestive system can yield dividends that can lead to a lifetime of health and wellness.